1. Field of the Invention
The present invention relates to the field of semiconductor devices and, more particularly, to a multi-chip package (MCP) and a method for manufacturing the same.
2. Description of the Related Art
Spurred on by new developments in semiconductor technology and user demands, recent trends in the electronics industry have been towards miniaturization and decreased weight. To meet these demands, multi-chip packages (MCPs) were introduced, which include a plurality of semiconductor chips in a single package.
Various three-dimensional MCPs have been developed, and in particular, new technology has been introduced for chip level stacking rather than package level stacking. The chip level stacking process interposes a thin substrate between the semiconductor chips and stacks the semiconductor chips by using solder or other materials, providing easy access to electrical interconnections at the chip level and to embodiments of chip size packages. The stack packaging method has the advantages of a simple manufacturing process and design flexibility. Furthermore, it may also be achieved by use of conventional processes. However, the stack packaging described above also has several drawbacks such as increased package thickness due to the insertion of the substrate, an increased manufacturing cost and poor heat dissipation, thereby limiting the stackable number of semiconductor chips. In order to overcome these problems, technology has been employed to form via holes in a wafer, fill the via holes with metal and vertically stack the semiconductor chips using solder bumps.
FIG. 1 is a cross-sectional view of a conventional MCP. As shown in FIG. 1, the conventional MCP 110 has a pad redistribution line 117 disposed toward the edges of a main surface of a semiconductor chip 111 and connected to a chip pad 113. A plurality of semiconductor chips 111 are vertically stacked using solder bumps 127. Each semiconductor chip 111 has a metal layer 125 that vertically penetrates the chip 111 and is connected to the pad redistribution line 117. A lowest semiconductor chip 111 is attached to a substrate 131. On the surface opposite to the chip-attached surface of the substrate 131 are formed solder balls 141. The solder balls 141 serve as external connection terminals.
The conductive metal layer 125 is formed by filling via holes 123 formed at the wafer level or the chip level with a metal. On the lower surface of the metal layer 125 are attached the solder bumps 127.
The stacking of the plurality of semiconductor chips 111 is achieved by attaching the lowest semiconductor chip 111 to the substrate 131 and then proceeding with a reflow, followed by the next chip, and then another reflow process, and so on. The solder bumps 127 of an upper semiconductor chip 111 are in contact with the conductive metal layer 125 of a lower semiconductor chip 111. Therefore, electrical interconnections are established in the stacked chips.
The conventional MCP eliminates the need for a separate interposer, thereby reducing the manufacturing cost and the package thickness. However, since the semiconductor chips are electrically interconnected using the solder bumps, adhesive strength changes due to warpage of the stacked chips and chip alignment failures may occur during the chip stacking process. The conventional MCP also requires several solder reflow steps and an additional substrate for stacking the semiconductor chips.